System and method for separating heavier and lighter components of liquid mixtures

ABSTRACT

A MIXTURE OF LIQUIDS CAPBLE OF GRAVITY SEPARATION. SUCH AS OIL AND WATER, IS CHARGED WITH GS OR AERATED IN A CYCLONE. THE ACERATED LIQUID MIXTURE IS THEN SEPARATED IN A FLOATATION CHAMBER OR CELL. THE LIGHTER LIQUID COMPONENT FLOATS TO THE SURFACE OF THE LIQUID MIXTURE IN THE FLOTATION CELL AIDED BY THE RISING GAS IN THE LIQUID MIXTURE. SEVERAL CYCLONE-FLOTATION CELLS MAY BE CONNECTED TOGETHER IN SERIES IN WHICH ARRANGEMENT THE HEAVIER SEPARATED COMPONENT MIXED WITH THE LIGHTER UNSEPARATED COMPONENT IS CYCLED FROM A PARTICULAR FLOTATION CELL TO THE NEXT SUCCEEDING CYCLONE-FLOTATION CELL.

Jan. 8, 1974 J. A. GARCIA SYSTEM AND METHOD FOR SEPARATING HEAVIBR ANDLIGHTER COMPONENTS OF LIQUID MIXTURES Filed Sept. 20, 1971 1 E1\'"TORJUAN A. (GARCIA JOHN S. SCHNEIDER,

GAS SOURCE A TTO R NE Y.

United States Patent O SYSTEM AND METHOD FOR SEPARATING HEAVIER ANDLIGHTER COMPONENTS OF LIQUID MIXTURES Juan A. Garcia, Houston, Tex.,assignor to Esso Production Research Company Filed Sept. 20, 1971, Ser.No. 181,989 Int. Cl. B01d 17/02 US. Cl. 210-44 14 Claims ABSTRACT OF THEDISCLOSURE A mixture of liquids capable of gravity separation, such asoil and water, is charged with gas or aerated in a cyclone. The aeratedliquid mixture is then separated in a flotation chamber or cell. Thelighter liquid com ponent floats to the surface of the liquid mixture inthe flotation cell aided by the rising gas in the liquid mixture.Several cyclone-flotation cells may be connected together in series inwhich arrangement the heavier separated component mixed with the lighterunseparated component is cycled from a particular flotation cell to thenext succeeding cyclone-flotation cell.

BACKGROUND OF THE INVENTION The present invention is broadly directed toa method and system for separating the components of a liquid mixture inwhich cyclones are used to force gas into the liquid mixture for thepurpose of later aiding in floating the lighter component of the mixturein a flotation cell.

SUMMARY OF THE INVENTION In accordance with the teachings of theinvention, the separation system comprises, briefly, a flotation cell; acyclone for aerating a mixture of liquids; means for introducing theliquid mixture into the cyclone; means for introducing gas into thecyclone for aerating the liquid mixture in the cyclone; means fortransferring the liquid mixture charged with gas from the cyclone to theflotation cell; means for discharging the separated lighter liquidcomponent from the flotation cell; and means for discharging theseparated heavier liquid component from the flotation cell. Theinvention also encompasses the method involved in operating theseparation system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration ofan arrangement of the liquid-liquid separator of the invention;

FIG. 2 is a view taken along lines 2-2 of FIG. 1;

FIG. 3 is a sectional view taken along lines 3--3 of FIG. 1; and

FIG. 4 is an isometric view showing the overflow trough with its outletduct.

DETAILED DESCRIPTION OF THE INVENTION As shown in FIG. 1, aliquid-liquid separation system indicated at separates liquid componentshaving different specific gravities from each other.

A series of flotation chambers, cells or compartments and cyclone orvortex liquid-gas mixers are shown. A flotation compartment 20 has acommon wall 21 with another flotation compartment 22, which in turn hasa common wall 23 with another flotation compartment 24. Compartments 20,22 and 24 are covered by a gas tight top 30. A vortex or cyclone 40 ismounted above compartment 20 and a liquid delivery tube 41 extends fromthe upper end of cyclone 40 into compartment 20. Another similar cyclone42 is mounted above compartment 22 and a liquid delivery tube 43 extendsfrom the top of cyclone 42 into compartment 22. A third cyclone 44 ismounted above compartment 24 :and a liquid delivery tube 45 extends fromcyclone 44 into compartment 24. As shown tubes 41, 43 and 45 terminatebelow the surface of the liquid in their respective compartments.Positioned just above the outlet of tube 41 is a perforated distributionplate 46. Each of the other tubes 43 and 45 is similarly provided with aperforated liquid distribution plate 47 and 48, respectively.

Gas is supplied to the compartments from a source indicated at 50. Thegas is located between the top 30 of the compartments and the level ofthe liquid indicated at (FIG. 3). The bottom of each cyclone is immersedin a gas layer as shown. Each of the compartments 20, 22 and 24 overflowinto a common trough 52 which extends the full length of the unit andwhich discharges into a discharge duct or conduit 56 through opening 54in the end wall of the unit. The up-turned lip of trough 52 de-.

termines the maximum liquid level in the compartments. Duct 56 extendsdownwardly into an outer compartment 58 with its open end 57 submergedin liquid so as to maintain a gas head above the liquid in the duct andalso above the liquid in the compartments 20, 22 and 24. Any solids inthe overflow into compartment 58 deposit on the bottom of thecompartment and may be drawn ofi? at suitable intervals through conduit59. As oil fills the compartment 58 it overflows into a collectionchamber 60 from where it may be discharged by way of conduit 61 to asump.

A pump 62 pumps the liquid mixture to be separated through a conduit 64into cyclone 40. Another pump 65 located in a conduit 66 pumps liquidfrom the bottom of compartment 20 into cyclone 42 and still another pump67 located in a conduit 68 pumps liquid from the bottom of compartment22 into cyclone 44. A conduit 70 extends from the bottom of compartment24 into a small compartment 71. Conduit 70 is adjustable in height incompartment 71 to establish the liquid level in compartments 20, 22 and24. Clean water is discharged from compartment 71 through line 72.

OPERATION In operation of the system a mixture of liquids and possiblysome solids, such as Water, oil and some sand, is delivered throughconduit 64 to cyclone 40 by means of pump 62. The bottom of cyclone 40exists in the gas environment. The vortex formed in the center ofcyclone 40 sucks gas up which mixes with the swirling liquid underpressure. The aerated liquid mixture from cyclone 40 is discharged intocompartment 20 through tube 41 and distribution plate 46. The rising gascharged in the liquid mixture in cyclone 40 floats oil and possiblylight solids to the surface of the liquid. Heavier solids are separatedin the cyclone 40 and dropped from the base thereof and remain suspendedby the gaseous froth on the surface of the liquid. The floated oil andsolids overflow into trough 52 and through duct 56 into compartment 58.When compartment 58 fills the oil overflows into compartment 60. Anysolids carried with the oil into compartment 58 may be dischargedthrough conduit 59. The heavier separated liquid along with theunseparated lighter liquid component mixed therewith is pumped by meansof pump 65 through conduit 66 into cyclone 42 where the mixing andcharging with gas is repeated. The liquids charged with gas aredischarged through conduit 43 into compartment 22 through distributionplate 47. Similarly, the heavier liquid component along with theunseparated lighter liquid component in cornpartment 22 is pumped bymeans. of pump 67 through conduit 68 into cyclone 44 where the liquidsare again charged with gas and are discharged through tube 45 intocompartment 24 through distribution plate 48. The heavier component isthen overflowed through conduit 70 into compartment 71 whence it isdischarged from the system through conduit 72.

The action of the liquids in the cyclone causes the gas to be sucked upthe center of the vortex formed by the swirling liquid mixture in thecyclone and beaten into the liquid to form small gas bubbles in theliquid.

The vortex or cyclone separators 40, 42 and 44 are of conventionaldesign and may be suitably of the type discussed and shown on pp.39323935 of the Composite Catalog of Oil Field Equipment of Services,1966-67 ed., published by World Oil. The inner wall of each cyclone ispreferably lined with a replaceable sleeve of material such aspolyurethane or butyl rubber which is durable. The gas may be methane(natural gas) or any suitable nonoxidizing, inert gas. Where oxidationis not a problem air may be used.

While the invention has been described herein with reference toseparating water and oil, other uses will be apparent to those skilledin this art.

Other changes and modifications may be made in the specific illustrativeembodiments of the invention shown and/or described herein withoutdeparting from the scope of the invention as defined in the appendedclaims.

Having fully described the apparatus, operation, advantages and objectsof my invention, I claim:

1. A system for separating heavier and lighter components of a liquidmixture comprising:

a flotation compartment;

a cyclone for charging said liquid mixture with gas;

means for separately introducing said liquid mixture and said gas intosaid cyclone; and

means for transferring the liquid mixture charged with said gas fromsaid cyclone to said flotation compartment at a location below thesurface of the liquid in said flotation compartment, the gas in saidliquid mixture aiding in floating the lighter liquid component to thesurface of the liquid in said flotation compartment.

2. A system as recited in claim 1 in which said gas comprises air.

3. A system as recited in claim 1 in which said gas comprises anon-oxidizing gas.

4. A system for separating heavier and lighter components of liquidmixtures comprising:

a first flotation compartment;

21 first cyclone for charging a liquid mixture with gas;

means for introducing said liquid mixture and said gas into said firstcyclone;

means for transferring said liquid mixture charged with said gas fromsaid first cyclone to said first flotation compartment, the gas in saidliquid mixture aiding in floating the lighter liquid component to thesurface of the liquid in said first flotation compartment;

a second flotation compartment;

a second cyclone for charging another liquid mixture with said gas,

means for introducing said other liquid mixture from said firstflotation compartment and said gas to said second cyclone, said otherliquid mixture comprising said heavier liquid component separated insaid first flotation compartment and any of said lighter liquidcomponent not separated in said first flotation compartment; and

means for transferring the other liquid mixture charged with said gasfrom said second cyclone to said second flotation compartment, the gasand said other liquid mixture aiding in floating the lighter liquidcomponent to the surface of the liquid in-said second flotationcompartment.

5. A system as recited in claim 4 including at least a thirdcyclone-flotation compartment unit for charging with gas and separatingthe lighter liquid component from the heavier liquid mixture separatedin the second flotation compartment.

6. A system as recited in claim 5 including means for discharging saidlighter liquid component separated in each of said flotationcompartments.

7. A system as recited in claim 6 including means for discharging saidheavier liquid component from said third flotation compartment.

8. A system as recited in claim 7 including means arranged in eachflotation compartment for distributing aerated liquid mixture overgreater area therein.

9. A method for separating liquids having different specific gravitiesfrom a mixture thereof comprising the steps of:

introducing said liquid mixture into a cyclone;

separately introducing gas into said cyclone to charge said liquidmixture with gas; and

transferring said liquid mixture charged with gas to a flotationcompartment at a location below the surface of the liquid in theflotation compartment in a manner so that the gas in said liquid mixtureaids in floating the lighter liquid component to the surface of theliquid in said flotation compartment.

10. A method for separating liquids having dilferent specific gravitiesfrom a mixture thereof comprising the steps of:

introducing a liquid mixture into a cyclone;

introducing gas into said cyclone to charge said liquid mixture withgas; transferring said liquid mixture charged with gas to a flotationcompartment, the gas in said liquid mixture aiding in floating thelighter liquid component to the surface of the liquid in said flotationcompartment;

aerating another liquid mixture in another cyclone, said other liquidmixture being the heavier liquid separated in said flotationcompartment; and

separating said heavier liquids from said lighter liquids in anotherflotation compartment, the gas in said other liquid mixture aiding infloating the lighter liquid component thereof to the surface of theliquid in said other flotation compartment.

11. A method as recited in claim 10 in which the mixing-aeration andflotation-separation steps are repeated until the heavier and lighterliquid components have been completely separated.

12. A method as recited in claim 9 in which the mixing-aeration andflotation-separation steps are repeated until the heavier and lighterliquid components have been completely separated.

I 13. A method as recited in claim 9 in which said gas 1s an.

14. A method as recited in claim 9 in which said gas is a non-oxidizinggas.

References Cited UNITED STATES PATENTS

